The ancient Greeks wrote several lists of ancient wonders. Each list had 7 selections because to the ancient Greeks 7 was a magical number. Many of the magnificent structures selected were located in ancient Greece, but not all of them.

The ancient Greeks loved lists. There
was a time period in which some Greeks attempted to create a list of
the most magnificent stuctures in the world they knew. They called
these structures "wonders". Wonders were sights or things to
be seen. The selection of 7 wonders acted somewhat like a suggested
tourist guide, or sights not to miss.

Most of the lists various Greeks created agreed with 6 of 7 wonders. It would be very hard to overlook the Pyramid at Giza
in Egypt, for example.
The legend of the Hanging Gardens of Babylon in ancient Mesopotamia
caught their romantic interest. Also found on most lists were the
Statue of Zeus at Olympia, the Temple of Artemis, the Mausoleum at
Halicarnassus, and the Colossus of Rhodes. But the Greeks were not
in agreement with the selection of the 7th wonder. Actually, they
never agreed. Philo's list is the one we use today. Philo was a Greek engineer
and mathematician. He selected the Lighthouse at Alexandria as the 7th wonder.

Some of the wonders that did not make Philo's list
included Babylon's Wall and the Ishtar Gate, both located in ancient
Mesopotamia. Another popular choice not on his list was the palace in Persia.
Many amazing structures were built in ancient times. Because the ancient Greeks
had limited
themselves to only 7 selections, various Greek writers had a difficult time agreeing on a list.
Here's Philo's list: